Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Radio Frequency Identification (RFID) systems may typically include RFID tags and RFID readers. An RFID tag may typically include an antenna comprising metal traces on a substrate, and an integrated circuit (IC) die. Conventional RFID tag assembly methods may require accurate alignment of an antenna layer and the IC to ensure proper coupling of the antenna to Radio Frequency (RF) distribution bus through connection patches. Commonly, the tag assembly may be performed using flip chip method, wherein an IC may be picked up and flip mounted on the substrate and may aligned to the prefabricated antenna traces on the substrate. Sometimes, metal bumps may be used to connect the antenna connections with RF pads on the IC. This means a post-processing step with high-precision die placement onto the antenna trace and tightly controlled die mount force may be required to apply the metal (gold) bumps. One of the disadvantage with this method is use of conductive adhesives that may require continuous pressure and heat during cure, resulting in limitations of assembly throughput. Other disadvantage is the cost of the materials and the assembly processes may typically comprise a large portion of the cost of the RFID tag.
Furthermore, for RFID tags, operating in the high frequency (HF) spectrum of the radio frequency band, for example at 13.56 MHz used for near field communications (NFC), loop antenna with multiple turns may be used. For loop antennas, having multiple turns, the antenna may usually be prepared with a multilayer process, including the fabrication of vias and a bridging metal layer, in order to connect the two terminals of the antenna. This multilayer process is much more expensive than a single layer process that may be used to prepare the loop or dipole antennas.
Accordingly, a need continues to exist to develop methods and systems that can reduce the handling cost and speed up the REID tag assembly process.